Welding current control apparatus



Dec. 1, 1942. c. H. RIPPL 2,304,921 WELDING CURRENT CONTROL APPARATUS I Original Filed Feb. 7. 1936 3 Sheets-sheaf, l

7 v} H N f 6 67 6/ x! 3 3 Z :2 650. U M f" I i 57 65 J7 2 3 /3 l0-1 4 m5 m5 3 L 2 I 0 m A4 L; 45 K COM PRESSED A I R SOURCE INVENTOR'.

CHARLES. H. RIPPL ATTORNEY.

Dec. 1, 1942..

c. H. RIPPL.

WELDIN'? CURRENT CONTROL APPARATUS Original Filed Feb. 7, 1936 3 Sheets-Sheet 2 INVENTOR.

CHARLES H. RlPPL BY EMZ KM 6. 4.4,

ATTORNEY.

Patented Dec. 1, 1942 I I I WELDING CURRENT CONTROL \APPABATUS Charles H. Rlppl, Cleveland, Ohio, aulgnor to The Clark Controller Company, Ohio, a corporation of Ohio Cleveland,

Application February 7, 1936, Serial No. cam Renewed July 24, 19:9

21 Claims.

This invention relates to fluid pressure actuated electric contactors for controlling electric welding current.

In some electric welding production processes, such for example as spot welding processes, it is desirable to make different welds. sometimes in succession, with currents oi dii'lerent time duration. Heretofore this has required a duplication 01 current controlling contactors, one for timing each kind of weld; or has necessitated a re-arrangement of the production flow plan to make all oi one kind of weld at one time and then readjust the timing apparatus for making the other kind of weld.

Also, it has been heretofore proposed to operate welding current controlling electric contaotors by compressed air or other fluid pressure from the source used to operate the welding sun itself, and under the control oi the gun operating valve, and while a marked degree of improvement over prior methods has. thereby been attained, in some instances the electric contactor has operated ahead of the gun; and re-setting oi the fluid operated apparatus alter an operation of the contactor has not been sumciently positive, quick or reliable.

It is therefore among the objects of this invention:

To provide an improved fluid pressure operated electric contactor tor welding current control;

To provide, in a. fluid pressure operated electric contactor for controlling welding current, an

improved fluid control valve means; 1

To provide a welding current control apparatus having improved contactor operating means whereby a plurality of welding guns may utilize welding current controlled by a single contactor and each gun supplied thereby with current of diflerent time duration;

To provide in a fluid pressure operated electric 'contactor apparatus for supplying current to a welding gun, improved means to insure operation oi the gun and contactor in the desired sequence; and to insure quick re-setting oi the contactor operating fluid pressure apparatus after an operation thereof.

Other objects will be apparent to those skilled in the art to which my invention eppertains.

My intention is My disclosed in the following description taken in connection with the accompanying drawings, in which:

Fig. l is a front eievational view, partly diagrammatic, of an apparatus embodying my invention, in a preierred form 2 is a fragmentary cm" sectional view taken approximately from the plane 2-4 of Fi 1;

W. 3 is a side elevational view taken iron the plane Hoi 1 with parts thereof in longitudinal section; Fig. 4 is a cross-sectional view taken from the plane H of Fig. 3;

Fig. 5 is a fragmentary view in elevation of some of the parts of Pig. 3 illustrated in section in that figure:

Fig. 6 is a fragmentary sectional view taken on a plane parallel to the plane oi! the paper and illustrating someoi the parts of Fig. 3 in section which are illustrated in elevation in that figure;

Fig. 7 is a cross-sectional view taken from the plane |--'I of Fig. 3;

Fig. 8 is a view generally similar to Fig. 3 but illustrating parts thereof in difierent operative positions;

Fig. 9' is another view illustrating fragmentarily, some of the parts 0! Figs. 3 and 8 in other operative positions thereof;

Fig. 10 is a fragmentary view similar to a part 0! Fig. 3 and illustrating a modification. 25

Referring to the drawings, 1 have shown generally at I a panel preierablviormed from insulating'material upon which is mounted a two-pole electric contactor comprising stationary contacts 2-2 supported on the panel -I by brackets H having incoming terminals 4 and I secured theretoto which incoming power lines 0 and 1 may be connected. 0n the panel I is mounted a pair of transversely spaced bearings 8 and I (Figs. 1, 2 and 3) in which are oscillatably supported opposite cylindrical ends it and H of a rectangular section shaft I! having a sleeve of insulating material l8 thereon. Arms "-44 are clampedupon the sleeve II and carry at their upper ends movable contacts Ii-ll, and out-going terminal; I and II are mounted on the panel I connected to the contacts ii--II by flexible conductors ll-ll.

Whentheshait l2 isoscillatedbymeanstobe described, the pairs or contacts "-4 are engaged and current may flow from the power lines 6 and i therethrough and out at the terminals lO-il in a well known manner, and the current may likewise be broken when the contacts are separated, the current flowing for the predetermined time duration that the contacts are held closed. impulses of welding current are thus supplied at the contacts is and n to a plurality such as two welding guns, illustrated generally at is and 2|. The guns illustrated are alike and each comprises a handle or hand grip 2! having a head 22 spaced therefrom and clamped thereto upon an intermediate housing 23 in the form of a pneumatic cylinder. A piston 24 reciprocates in the cylinder and reciprocates a piston rod 25 guided in the head 22, in the retracted direction by a spring 26 in the cylinder and in the operated direction by compressed air admitted to the cylinder through a duct 21 in the handle.

Secured to the piston rod is one welding electrode 2! movable relative to another electrode 29 supported on the head 22 by a yoke 33. Work to be welded, shown at 3|, is clamped between the electrodes 28 and 2! when air is admitted to the cylinder, and when the contact pairs 2-" are closed, current will flow, say, from the terminal .11 by a wire 32 to the contactor 28, through the 15 work 3| to the contactor 23, and thence by a wire 33 back to the terminal 18, to work. Compressed air is admitted to the cylinder 23 from a source 33 by a conduit 35 and a branch concluit 36 connected to the handle 2 l. A piston valve 31 in the handle, when operated by a compressible button 38, will admit compressed air from the branch conduit 36 to the duct 21 to operate the gun as described. When-the valve button 33 is released, air in the cylinder 23 may ilow back through the duct 21 and out through the valve at an outlet duct 33. When air is thus admitted by the valve 31 to the gun, airis also admitted from the duct 2'! through a duct 33 to a conduit (I to operate the contact pairs 2-45 by means to be described which holds the contacts closed for a predetermined impulse time interval; so that by the single operation of pressing the valve button 38, the electrodes are engaged with the work and an impulse of weldin current, accu- :ately timed, flows therethrough to make a weld. The contactor contacts are operated as will be described, after the operation or the gun because oi the time required for the back pressure in'the 4G cylinder 23 and hence in the conduit 4! to build up to a ccntactor contact operating value.

The gun in may be exactly like the sun 1'! above describedreceiving compressed air through a branch conduit 42 and receiving current through 4 wires 43 and 44 from the terminal: 16 and l! and amnitting air to a contact-operating conduit #5. The pneumatically operated means for closing and. opening the contact pairs i----! will now be described. As shown in Figs. 3, 4, 6, 8 and 9, an arm 43 is rigidly secured to the rectangular shaft :2 by being clamped thereon by a clamp ll and bolts -48, so that -sciilat-sry movement of the and 6 will positively oscillate the contactcarrying shaft 12. a: 46 is stopped in one direction by an adjustable- 33 in the lower end thereof which adiustahly chimps a weight 5! upon the lower end of the arm for inertia 2W5. At the upper end of the arm 55, a stud 5! is rigidly clamped therein in a slottedop" g by a screw 52 and extends opposite t s therefrom and each projecting end as thereon latchdorm cam n i Si having ro le s -5 and 59 T I iuoEiDSfi in a.

street a weld at the e back of the arm 16, .i wound around ends of the 5; anchored the free one. engaging si .s 58- mission of. air to the cylinder 14 may be adjustably controlled. When adjustwise position to engage the stop bolt 48 with a stopblock 5! on the panel I by a spring 60 abutting at opposite ends upon the panel I and upon an adjustable screw 61 on the arm 46 above the shaft l2]:

A irame '12 is secured to the panel I and at the forward portion thereof has aligned vertically spaced bores 63' and 83 in which reciprocates a plunger 63, held-against rotation by a key 66 secured to the frame and projecting into a keyway I31 in the plunger.

A compression spring 61 reacting at its lower end upon the plunger aridat its upper end upon a washer 58 onthe lower end-oi a screw 69 in an arm 13 projecting upwardly from the frame 82, yieldingly holds the plunger downwardly, normally, the plunger having a shoulder]! resting upon the frame 61 at the upper end of the bore 63. The spring "may be adjusted by the screw 39 to vary the spring force by which the plunger is returned downwardly to its normal downwardly stopped position, shown in Fig. 3.

The lower end oi the plunger 35, where it reciprocates in the bore 33, is of reduced diameter providing the said shoulder II and the reduced diameter portion constitutes a piston rod 12 proiecting downwardly into a tubular cylinder 13 having on its lower end a piston 13.

In a manner to be described, fluid under pressure such as compressed air is admitted to the cylinder 13 from the conduit 4| above described and thereupon the piston H pushes the plunger 3' upwardly against the opposing compression oi the spring 31. fIhe plunger has thereon a cam 15 having an inclined cam face 13 which, as the plunger moves upwardly, engages the roller 53, as shown in Fig. rocking the arm 3| clockwise as viewed in Fig. 3 and rotating'the shalt i2. This moves the movable contactor contact l5, shown diagrammatically in Fig. 3, into engagement with the stationary contactor contact I, the parts then being in the position shown in Fig. 8.

The cam 15 passes tree oi the roller 5'5, with a quick movement so that the motion of the arm 43 is continued due to the inertia of the weight 80. The spring 60, which may be suitably adjusted as described, quickly returns the arm 46 counterclockwise disengaging the contacts i5 and Z, the parts moving to the position shown in Fig. 9, so that the contacts remain closed for only a short interval oi time determined by the inertia of the weight 59 and the tension oi the spring 83. As will be described hereinafter, the rate of ad- 13 under the piston ed so as to appreciably retard the air admission, the velocity of movement 0! the plunger will he reduced. Thus if desired, the plunger may be made to move so'slowly that the contacts 15-2 wih remain c osed by engagement of the cam face I with the roller 56 or a relatively long ubstantially independently oi the inertia The inertia of the weight 50 the time duration of the con to e very short.

occurs under piston I4 is 8? moves the plunger 6! downwardly rapidly, from the position of Fig.

" i to that 01 Fig. 3, and the cam ii sides over the roller 55 which is new in the path of the cam by r g the corn follow r H, We shown in Fig. 9. e rider l3 and pis ten .16 w be described. With the part in. normal position oi Fig. 3, hold such as 3,304,021 under pressure is admitted through the conduit II and passes upwardly through a vertical duct 11 and thence by a horizontal duct 18 where it encounters a vertically reciprocable piston valve 19, the air flowing around the valve in an annular groove 80 in the valve and continues through a duct H (see also Fig. 7), and thence around a needle valve 82 to a valve chamber 83 and duct 84, and thence to an annular groove 85 communicating with a duct 86 which opens into a vertical duct Cl, the latter communicating with the lower end of the cylinder 13 below the piston 14.

The air thus flows to the cylinder under the control of the needle valve 82 so that the velocity of the plunger 65 and its cam 15 may he adjusted, the needle valve iunctionirig as a throttle valve, andinasmuch as the velocity of the cam 15 when it engages the roller I6 will determine the extent of inertia throw as above described of the arm 6 and therefore determine the length of the time that the contacts |--2 are closed and the length of the current duretion the current duration may be adjusted by adjusting the needle valve 82, and it therefore is rendered read ily adjustable by having a threaded shank to threaded into the wall of the chamber 33 by which the needle valve 82 may be adjusted. A lock nut 82 is provided to fix the adjustment and the threaded shank 88 has thereon a dial head it: cooperating with a fixed ringer St to indicate its adjusted position. mus, by turning the dial head 52 to various numbered dial positions, the duration of the current impulse may he adjustably changed, and indicated when air is admitted to the cylinder 73 as just decor-lived and the piston l4 shoves the plunger upward, upward movementis stopped hr a collar 32 on the piston rod engaging the frame at 33,, Fig 5. As the plunger approaches the top of its stroke, the piston valve 19 is 'shiited u wardlv as follows. The upper end of the piston valve l8 projects upwardly and has threaded into its upper end a rod 9% which passes through an eye secured to the plunger 65 and on the upper end oi the rod 84 are look nuts 96 constituting a shoulder on the red, the loci: nutsbeing adjustable on l'llfi to adjust the position of shoulder. i

The upward movement of the zinger 6%, therefore moves the eye 8%; upwardly and it enthe ehonitier :36 and accordingly raises the valve "58 a predetermined distance and accurate is; when the collar i on the piston rod 12 ehgagee its stop 93. v

ital in the valve to is thereby raised and the valve closes the duct l8 and 8% so that iur flew of field to the evil l; is thereby out At the some time, the g2 as provides a r loehargc outlet for air in the cylinder, the air flowing clowmvarrlly throu e ti, laterally through the e5, ie groove into a duct thence arch; annular groove 8% through apricot $8, llr outward through an opening at (eee als in e; which opening is adjusts in size lair ital hrearierl into it partly overlapping the alcove de it merrily and avoid shock when the shoulder it strikes the Irameas above described.

The piston valve 1| is held in its upper or discharge position while the plunger is descending by air pressure supplied from the vertical duct 1! through a small duct m, the air passing around a reduced diameter portion 2 at the lower end of the valve-ll and into a chamber Ill below the valve 19, the pressure in the chamber M3 being kept at a low value by constantly eecap ing through a restricted orifice I'll in the chamber wall. The pressure in the chamber I", however, is sumcient to hold the valve 1! in its upper position, Fi 8, so that it remains in said position after the plunger '5 descends so long as the operator holds the valve button 38, Fig. l, depressed andcontinues the supply of air to the conduit ll. In other words, the operator must remove pressure from the button H to permit the valve II to reset. thus insuring a complete cycle of operations in each case.

when pressure in the chamber III is thus released. thepiston i9 is moved downwardly by a spring Ill which is at all times pushing downwardly on the valve, the spring reacting at one end upon the valve and at the other end upon a. bracket Md secured to the frame 82. In its downward movement, the valve is stopped by a shoulder till on the valve. y

when the valve 18 moves to its lower position, the full diameter or main portion of the valve closes the duct NI so that the chamber it! is zemrerl to atmospheric pressure by the orifice ifi t. The valve I! may beprevented from overtravelingnpwardly by inertia by means of a pin or spring ring in .on the lower end of the valve engaging the lower end of the wall of the bore in which the piston valve 15 reciprocates.

it will he apparent from the foregoing closeup tlon that when an operator depresses a gun valve button as as in Fig. 1, the plunger 55 will be given an up stroke at a predetermined controlled velocity which will close the contactor contacts 2 and ill fora predetermined length'of time to give 'a'welding current impulse to the welding gun, and a the plunger 35 will immediately return to its down position; the movement of the plunger operating the valve I9 to change it from the air intake to the air exhaust position and the valve 19 will remain in its operated position until the operator takes hand off from the gun hutpl'shiger are corresponding parts such as those dc serihed for the plunger 65., both sets parts hesopported on the common bracket 2 and both. phrngerie operating to move the common con teeter-operating arm 18 on the shaft II, the plunger, operating the contactor by air admitted through the conduit I for the gun l9 and the plunger in operating the some contractor contacts by air admitted through the conduit 48 to supply current to the gun 2|. a

In each case, the contactor will not be operatecl until the pressure in the conduits H or 45, has built up which occurs after the electrodes of the gun have engaged the work and the h anger cushioned to ream-e 25 is operated it will produce a current hope pro-air are the gun cylinder has accordingly built cpl The velocities of the two plungers may he ash his ed as above described so that when plunger operates it will produce current imp of one time duration and when other chi different time duration under the control or the same contacts 2--I S. Therefore, in doing production work, an operator may operate the gun II to produce, say, short time-spot-welds, and for a long-time spot-weld may lay that gun down and pick up the gun 20 and perform such welds with it. Thus, welds of diflerent current time duration may be performed one after the other without a transfer of the work from one station to another in the plant or production line and utilizing a single pair of contactor contacts and a single panel supporting the same.

As a further means of adjusting the duration of the current time, the cam I5 is rendered adjustable by being formed separately from the plunger 65 and projecting laterally therefrom and having a plurality of shims I09 between the cam and the plunger to position it farther from or nearer to the line of motion of the plunger so that it will engage the roller II earlier or later in its upward travel.

As statedabove, there are two cams II and "a (see Fig. 4), one for each plunger II and 65a, and these may be adjusted separately and differently if desired by shims such as the shim Ill shown in Fig. 3 in connection with the cam 15.

The entire valve control above described may be constructed as a unit to adapt it to be removed and replaced if desired for the usual purposes, and one such unitary construction is illustrated in Figs. 3 and 8. The cylinder 18 is screwthreaded at its upper end into the frame '2 and into its lower end is screw-threaded a plug III having therein the ducts i1, 88 and the annular groove-851A head I on the plug III clamps, between it and the lower end of the cylinder 13, a housing I I2 in which are formed the ducts ll, ii, 91, 98, IN, IS and 78, as well as a bore for the valve I8. A supplemental housing III secured to the lower side of the housing II! provides the chamber I08 and a receptacle for the end of the conduit AI. A bracket I" may be clamped between a shoulder on the upper end of the-cylinder 1i and the lower side of the housing 62.

In Fig. I have illustrated a modification of the valve control which it may be desirable to employ in some cases tor the following reasons. In some instances, because of the sluggish movement of th plungers of the gun II or 2| and the pressure of the compressed air source and the necessary length of the conduit H or 4|, the contactor operating plunger 85 or "a may be operated more rapidly, that is to say, ahead of the operation of the gun to engage the electrodes 2829 with the work II; or. the contacts Il-l may be initially engaged before initial engagement of the electrodes with the work. The obvious remedy would be to increase the resistance or downward force of the spring 81 opposing movement of the plunger 55 to delay its move-- ment until greater pressure had built up in the cylinder 13 to insure operation of the gun before the contactor. But this would introduce another dlfiiculty, namely, that with such a powerful spring 61, its force would rapidly increase when it was further compressed by upward movement or the plunger 85 so as to make the movement of the plunger sluggish and deprive it of the necessary surplus of energy to reliably operate the contactor operating arm 46 with th desired quick positive action. Resort would then have to be had to an increase of size or the cylinder 73 and then the original difllculty of too quick an operation of the plunger 55 would again be present and so on.

By utilizing the modification of valve control illustrated in Fig. 10, admission of air to the cylinder I3 is delayed until a predetermined pressure at the valve control, or adjacent the admission end of the cylinder 13, has been attained, such pressure being sufilciently high to insure that the gun electrodes have engaged the work, and to insure positive movement or the plunger at not less than a certain predetermined velocity and this will now be described.

The supplemental housing III of the first described form is in this form increased in horizontal extent toward the left as viewed for example in Fig. 3 of the other form and is indicated at I. A preierably but not necessarily horizontal cylinder II! is provided in the housing Ill and the conduit ll communicates with the inner end thereof by a duct II, substantially at the axis of the cylinder III. A duct I II also communicates at one end with the cylinder III radially laterally oi the point of communication therewith of the duct III, the duct III communieating at its other end with the above described vertical duct IT.

A. cup-form piston III is reciprocable in the cylinder III and has extending axially from the closed end thereof a small diameter portion III functioning normally as a valve to seat upon and close th open end of the duct II. A spring III projecting into the piston III reacts thereon at one end to normally hold the valve portion I II in seated position and reacting at the other end upon the inner end or an adjusting screw III proJect-' ing into th end of the cylinder III, and adJust-' able to vary the tensionof the spring I20, the adjustment being fixed by a lock nut I.

In operation or this modification, when the gun valve button 88 is depressed 'to admit air to the gun, the same pressure is applied to the conduit ll but does not immediately pass into the vertical duct 11 to operate the plunger ll as above described, being stopped at the valve portion III sealing the duct III. The pressure rapidly builds up and ultimately is sumcient to operate the gun to engage its electrodes with the work II. At this time the increasing pressure has reached a value in the duct I I8 sufflcient to remove the valve portion III therefrom against the tension of the spring Ill, and immediately thereafter the larger area of the entire end of the piston II! is exposed to that pressure and the piston I I8 is quick- 1y retracted against the spring tension, opening the duct II! to the pressure of the compressed fluid in the conduit 4i and operating the plunger 65 as above described.

By this means, the spring I20 can be adjusted to cause the piston I II to be moved either slightly before, or at, or slightly after the engagement of the electrodes of the gun with the work, and it is thus insured that the electrodes will be engag d with the work when the current controlling contacts engage; and since pressure is not admitted to the cylinder 13 until the moment when it is desired to hav the plunger 85 moved, the spring i! resisting movement of the plunger need not be a powerful spring with the disadvantages of such springs above described, but, in fact, may be only strong enough to quickly and positively return the plunger 55 to its normal position after operation thereof, which includes of course rocking of the cam followers I3 and N; and by these means, when the plunger starts to move it will always move with a positive movement and ata velocity not less than that corresponding to the pressure required to move the piston I ll; and 8;

- of my invention without sacrificing its advantages and within the scope of the appended claims. To illustrate, the valve control comprising the housing H2 and the supplemental housing H3 or I is illustrated as composed 01 pieces of block-fonn secured together, but such valve control may all be assembled in a cast-form housing of radically different appearance and with a diflerent arrangement of the various ducts therein but per- 1 forming the same functions as are the form illustrated and described.

Subject matter illustrated and described herein but not claimed is claimed in the co-pending application of Edward G. Beiderman, Serial Number 84,981, filed June 13, 1936, for Improvements in time controlled electric switches, and in my co-pending application Serial Number 167,636, flied October 6, 1937, for Improverents in fluid pressure operated apparatus, to which reference is hereby directed.

'I claim:

1. In a welding current control contactor o! the type comprising a stationary contact and a movable contact, an oscillatably supported element connected to the movable contact to move it to engage and disengage the contacts and'means normally constraining itto move to contact-disengaged position, a plurality of fluid pressure cylinder and piston type devices having each a pressure movable element, mechanism means operable by movement of either pressure moved element in one direction to move the oscillatably supported element to engage the contacts and to then permit it to return to contact-disengaged position, and maintaining the contacts engaged for a time period proportional to the velocity of the movable element, a source oi fluid at a predetermined pressure, separate conduit means for conducting fluid under pressure to each of the cylinders 01' the piston and cylinder devices, a corresponding plurality of valve means each for admitting and performed by cutting oflf flow of fluid from the source through the separate conduit means to one of the cylinders of the cylinder and piston devices, and means separate from said valve means to adjustably flx the rate of admission to one cylinder relative to another, to adiustably fix the relative velocities of the corresponding movable elements and thereby adjustably fix the time duration of engagement of the contacts.

2. The combination described in claim 1 and in which the said air admission adjustment means comprises a flow throttle valve in the conduit means to each cylinder operable to vary the flow rate by rotating it and a dial type means for indicating the adjusted position of each throttle valve, to indicate the time duration of engagement of the contacts.

3. In a fluid pressure actuated device for operating the contacts of a welding-'current-control contaotor, a fluid pressure chamber, a contact operating movable element movable by fluid pressure in the chamber, and biased to return to a normal position upon release of pressure in the chamber, a source 0! fluid pressure, conduit means communicating with the source and with the chamber, an operable valve controlling the conduit means to admit fluid to the chamber, a cut-oi! valve controlling flow in the conduit means, means rendering the cut-off valve operable by a press'ure-eflected movement of the pressure movable element to cut oil fluid pressure from the chamber to permit the pressure movable element to return to normal position independently of the operable valve, and means to maintain the cut-on valve operated so long as the operable valve is maintained operated.

4. In a fluid pressure actuated device for opcrating the contacts of a welding-current-control contactor, a fluid pressure chamber, a contactor operating movable element movable by fluid pressure in the chamber, and biased to return to a normal position upon release of pressure in the chamber, a source of fluid pressure, conduit means communicating with the source and with the chamber, an operable valve controlling the conduit means to admit fluid to the chamber, a cut-off valve controlling flow in the conduit means, means rendering the cut-oi! valve operable by a pressure-eflected movement of the pressure movable element to cut of! fluid pressure from the chamber, means for applying fluid pressure from the source under control of the operable valve to hold the cut-off valve in operated position until the operable valve is restored and means to then restore the cut-oi! valve.

5. In a fluid pressure actuated device for operating the contacts of a welding-current-control contactor, a fluid pressure chamber, a contact operating movable element movable by fluid pressure in the chamber, and biased to return to a normal position upon release of pressure in the chamber, a source of fluid pressure, conduit means communicating with the source and with the chamber, an operable valve controlling the conduit means to admit fluid to the chamber, a cut-off valve, controlling flow oi fluid to and from the chamber and biased to take up a normal flow position, a connection between the pressure inovable eiement and the cutofl valve to move it to an operated position to cut oil. fluid pressure to the chamber and to open an exhaust outlet from th chamber to permit the pressure movable element to return to normal position, and fluid pressure operated means to hold the cut-oi! valve in valve.

6. In a fluid pressure actuated device for opcrating the contacts of a welding-current-control contactor, a fluid pressure chamber, a contact operating movable element movable by fluid pressure in the chamber, and biased to return to a normal position upon release of pressure in the chamber, a source of fluid pressure, conduit means communicating with the source and with the chamber, an operable valve controlling the conduit means to admit fluid to the chamber, a cut-oi! valve. controlling flow of fluid to and from the chamber, biased to take up a normal flow position, a connection between the pressure movable element and the cut-oi! valve to move it to an operated position to cut 01! fluid pressure to the chamber and to open element to return to normal position, a valve chamber. conduit means controlled by the cut-off valve communicating pressure to the valve chamber from the source upon operation of the cut- 03 valve, and the cut-oil valve being held in cutan exhaust outlet from the chamber to permit the pressure movable oi! position by pressure in the valve chamber under control of the operable valve.

7. In a fluid pressure actuated device for operating the contacts of a welding-current-control contactor, a fluid pressure chamber, a contactor operating movable element movable by fluid pressure in the chamber and biased to return to a normal position upon release of pressure in the chamber, a source of fluid pressure and conduit means communicating with the source and with the chamber, an operable valve controlling the conduit means to admit fluid pressure to the chamber, a piston valve in the line of the conduit means having a normal fluid pressure admitting position, a connection between the pressure movable element and the valve to move it to a cut-oi! position, an outlet conduit means item the pressure chamber normally closed by the piston valve and opened upon movement thereof to cut-of! position, to permit the pressure movable element to return to normal position, a valve chamber communicating with one end of the piston valve, conduit means for communicating fluid pressure to the valve chamber upon movement 01 the valve to cut-of! position, a restricted constantly open escape port from the chamber to effect holding of the cut-oi! valve in cut-ofl position so long as the operable valve is maintained operated and to permit it to be relieved through the escape port to reset the cut-of! valve when the operable valve is restored.

8. In a fluid pressure actuated device for operating the contacts of a weldingcurrent-control contactor, a fluid pressure chamber, a contact operating movable element movable at different velocities by fluid in the chamber at various pressures in a range of pressures and biased to return to a normal position upon the release of pressure in the chamber, a source of fluid pressures variable over said range oi! pressures, conduit means communicating with the source and with the chamber, an operable valve controlling the conduit means to admit fluid to the chamber, a cut-oi! valve controlling flow in the conduit means, means rendering the cut-oi! valve operable by a pressure-eiiected movement of the pressure movable element to cut of! fluid pressure from the chamber to permit the pressure movable element to return to normal position independently of the operable valve, means to maintain the flow control valve operated so long as the operable valve is retained operated, and a yieldable normally closed valve in the line of the conduit means responsive to open to admit fluid pressure to the chamber to move the movable element, only at fluid pressure above the minimum pressure of said range to insure movement of the movable element at velocities above a minimum velocity.

9. In a fluid pressure actuated device for operating the contacts of a welding-current-control contactor, a fluid pressure chamber, a contacter operating movable element, movable at diiierent velocities by fluid in the chamber at various pressures in a range of pressures, a source of fluid pressure variable over said range of pressures, conduit means communicating with the source and with the chamber, an operable valve controlling the conduit means to admit fluid to the chamber, a cut-oil valve controlling flow in the conduit means, means rendering the cut-oil valve operable by a pressure-effected movement of the pressure movable element to cut oil fluid pressure from the chamber, means for applying fluid pressure from the source under control of the operable valve to hold the cut-oi! valve in operated position until the operable valve is restored and means to then restore the cut-of! valve, and a yieldable normally closed valve in the line of the conduit means responsive to open to admit fluid pressure to the chamber to move the movable elements, only at fluid pressure above the minimum pressure 0! said range to insure movement of the movable element at velocities above a minimum velocity.

10. In an electric contactor mechanism, an electric contactor, an electric circuit controlled thereby, a fluid pressure chamber, an element movable upon application of pressure to the chamber, mechanism actuated by movement of the movable element to flrst eflect closing and then eflect opening of the electric contactor to eflect a current impulse in the circuit of duration commensurable with the velocity of the movable element, the movable element being capable of moving at diiierent velocities commensurable with different pressures in the chamber, a fluid pressure source at variable pressure, operable valve means and conduit means controlled thereby i'or eflecting communication of pressure from the source to the chamber, and automatic valve means responsive to fluid pressure to control the admission of pressure to the chamber to prevent admission thereof except at pressures above a predetermined minimum to insure the eflecting of current impulses in the circuit of duration below a predetermined maxi mum.

ll In an electro-pneumatic mechanism, an electric contactor, an electric circuit controlled thereby, a fluid pressure chamber, an element movable upon application of pressure to the chamber, mechanism actuated by movement oi the movable element to flrst eflect closing and then eii'ect opening of the electric contactor to effect a current impulse in the circuit of duration commensurable with the velocity of the movable element, the movable element being capable oi moving at different velocities commensurable with diflerent pressures in the chamber, a fluid pressure source, a pneumatic apparatus, operable valve means and conduit means controlled thereby to eflect communication of source fluid pressure to the apparatus, the apparatus comprising means energized by the said electric circuit and comprising means at which fluid pressure rises, conduit means communicating the said rising pressure to the said chamber, and automatic valve means responsive to said rising fluid pressure to control the admission of said pressure to the chamber to prevent admission thereof except at pressures above a predetermined minimum to insure the effecting of current impulses in the circuit of duration below a predetermined maximum.

12. The mechanism described in claim 10 and in which the automatic valve means comprises a port in the line of thelline of the conduit means to the chamber and a valve spring-pressed in the direction to normally close the port and yieldable at pressures above the predetermined minimum to open the port.

13. In a fluid pressure actuated electric contactor mechanism, operable contactor contacts, a fluid pressure chamber, an element movable by fluid pressure in the chamber to operate the contacts, a source of fluid pressure, conduit means for conducting fluid under pressure from the source to the chamber, an operable valve operable to admit fluid pressure from the, source to the chamber, a control valve to admit pressure from the conduit means to the chamber, means causing the control valve to operate upon pressure eifectedmovement oi the movable element to reducethe fluid pressure in the chamber, and means to maintain the valve operated so long as the operable valve remains operated.

14. In a fluid pressure actuated electric contactor mechanism, operable contactor contacts, a fluid pressure chamber, an element movable by fluid pressure in the chamber to operate the contacts, a source of fluid pressure, conduit means for conducing fluid under pressure from operated so long as the operable valve remains operated.

15. In a fluid pressure actuated electric contactor mechanism, operable contactor contacts, a fluid pressure chamber, an element movable by fluid pressure in the chamber to operate the contacts, a source of fluid pressure, conduit means communicating source pressure to the chamber, a control valve to admit pressure from the conduit means to the chamber, means causing the control valve to operate upon pressure eflected movement of the movable element to reduce the fluid pressure in the chamber and means operable responsive to source fluid pressure in the conduit means to maintain the valve operated.

16. In a fluid pressure actuated electric contactor mechanism, an electric contactor comprising operable contacts, a fluid pressure chamber, an element movable by fluid pressure in the chamber at velocity commensurable with the pressure, a mechanism actuated by movement of the movable element to efiect operation of the contactor contacts and maintain them operated for a time period commensurable with the velocity of the movable element, a source of variable fluid pressure, valvecontrolled conduit means to admit pressure of the source to the chamber, automatic valve means responsive to fluid pressure to control the admission of pressure to the chamber to prevent admission thereof except at pressures above a predetermined minimum to insure movement of the movable element at velocity above a predetermined minimum to thereby insure operation of the switch for a time period below a predetermined maximum.

17. The contactor mechanism described in claim and in which the automatic valve means comprises a valve port normally ciosed by a spring-pressed valve and comprises means to cause a quick port-opening movement of the valve when the fluid pressure is above the said predetermined minimum.

18. The contactor mechanism described in claim 10 and in which the automatic valve means comprises a valve port and a spring-pressed piston valve of greater transverse area than the port and covering the port and the valve is moved to open the port at fluid pressure above the said predetermined minimum and thereupon it exposes the valve to the fluid pressure to efiect a quick opening movement of the valve.

'19. In an electric contactor mechanism, an electric contactor, an electric circuit controlled thereby, a fluid pressure chamber, an element movable upon application of pressure to the chamber, mechanism actuated by movement of the movable element to flrst eflect closing and then effect opening of the electric contactor to effect a current impulse in the circuit of duration commensurable with the velocity of the movable element, the movable element being capable of moving at diflerent velocities commensurable with different pressures in the chamber, a fluid pressure source at variable pressure, operable valve means and conduit means controlled thereby for. eflecting communication of pressure from the source to the chamber, and automatic valve means responsive to fluid pressure to control the admission 0! pressure to the chamber to prevent admission thereof except at pressures above a predetermined minimum to insure movement of the movable element at velocities above a predetermined minimum velocity.

20. In an electric welding equipment, a welder having relatively movable electrodes arranged in an electric circuit, a fluid pressure supply line, means for introducing fluid under pressure from the supply line into the welder, means responsive to the fluid under pressure to relatively move the electrodes into engagement with the work, air

pressure supply and distributing lines normally I out oi communication with each other, a switch communicating with the distributing line and located in the circuit to the electrodes to control said circuit, a valve controlling communication between said air lines and movable to open position by the fluid pressure flowing through the flrst named fluid supply line to the welder to eiiect an operation 01 the switch to close the circuit to the electrodes, means responsive to the fluid pressure supplied to the switch from the air distributing line to open the switch in timed relation to closing of the circuit. and adjustable means for regulating the last named means to control the time interval between closing and opening said circuit by the switch.

21? In electric welding equipment, a welder having relatively movable electrodes arranged in an electric circuit, means for introducing fluid under pressure into the welder, means responsive to the fluid under pressure to relatively move the electrodes into engagement'with the work, fluid pressure supply and distributing lines normally out of communication with each other, a switch communicating with the distributing line and located in the circuit to the electrodes to control said circuit, a valve controlling communication between said lines and movable to open position by the fluid pressure supplied to the welder to effect an operation or the switch to close the circuit to the electrodes, means responsive to the fluid pressure supplied to the switch from the distributing line to open the switch in timed relation to closing of the circuit,'and means also responsive to the fluid pressure supplied to the switch by the distributing line to exahust the is opened by the latter.

CHARLES H. RIPPL. 

